Explosive fastener driving tool

ABSTRACT

An explosive fastener driving tool of the &#39;&#39;&#39;&#39;push to fire&#39;&#39;&#39;&#39; type comprises a barrel which is axially slidable and rotatable in a receiver to and from breech closed and locked position. The receiver pivotally supports a safety pawl slidable in a longitudinal slot in the barrel to return a driving ram therein to its initial operating position. Additionally the pawl prevents tool cocking unless the barrel is locked in operating position. The pawl is removed from the barrel by breech locking movement to allow the ram to impact a buffer in the event of overdrive thus avoiding damage to the pawl.

United States Patent 1191 Shamaly Jan. 22, 1974 EXPLOSIVE FASTENER DRIVING TOOL Prima Examiner-Granville Y. Custer Jr. 1 Th P.Sh 1 Shlt ,c i [75] mentor omas ama e on Attorney, Agent, or Firm-Carl E. Johnson et al. [73] Assignee: USM Corporation, Boston, Mass. 221 Filed: May 23, 1972 [57] sT An explosive fastener driving tool of the push to fire [21] APPL N05 256,085 type comprises a barrel which is axially slidable and rotatable in a receiver to and from breech closed and 52 us. c1. 227/8, 227/10 locked position The receiver pivotally pp a 51 Int. Cl. B25c 1/14 safety p slidable in a longitudinal Slot in the barrel [58] Field of Search 227/8, 9, 10, 11 to return a driving ram therein to its initial Operating position. Additionally the pawl prevents tool cocking 56] References Cited unless the barrel is locked in operating position. The UNITED STATES PATENTS pawl is removed from the barrel by breech locking 3 494 125 2/1970 R 227m) movement to allow the ram to impact a buffer in the 3:543:986 mlgm 227") event of overdrive thus avoiding damage to the pawl. 3,549,074 12/1970 Brunelle 227/10 10 Claims, 5 Drawing Figures PATENTED JAN 22 I974 BACKGROUND OF THE INVENTION This invention pertains to explosive fastener driving BRIEF DESCRIPTION OF PREFERRED EMBODIMENT Referring mainly to FIG. 1, a tool generally desigtools of the type employing a captive driving rarn recipnated comprises a barrel 12 (FIGS. 1 and 5) longiturocable axially in a barrel. The fastener is. muzzle loaded, and a charge such as a cartridge is loaded in a breech bore of the barrel. The breech is locked by rota.- tion of a safety collar that prevents air firing. Thereafter the tool is cocked by pressing its muzzle against a surface, usually concrete or metal, into which the fastener is to be driven.

The prior art hashitherto taught the use of a longitudinal slot in a barrel, and means engaging in the slot for returning a driving ram to its starting position inthe tool. An example of such a tool is disclosed, for example, in U.S. Pat. No. 3,348,751 as well as-an earlier U.S. Pat. No. 3,066,302.

SUMMARY OF THE INVENTION It is an object of this invention. to provide an iming a captive ram and which shall be capable of safely and efficiently driving a range of fastener loads with conventional charges.

Another object of the invention is to provide a ramtype fastener driving tool of simple construction wherein cocking can not be effected unless a barrel for the ram is locked in breech closed position.

A further object of the invention is to provide, in a tool of the type indicated, means whereby a barrel for the ram can not be unlocked when the tool is cocked in the firing position.

To these and other ends a feature of this invention resides in the provision of a tool having, in, combination, a receiver, a barrel slidably carrying a ram and axially movable and rotatably mounted in the receiver, the barrel being formed with circumferentially interrupted sets of threads lockable in breech-closed relation and having a longitudinal slot extending forwardly thereof between two of such thread sets, and a pawl pivotally carried by the receiver and adapted, when the barrel breech is unlocked, to be engaged in the barrel slot. As herein shown the pawl is spring-urged to interengage with the barrel slot.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features of the invention, together with novel details and combinations of parts, will now be more particularly described in connection with an illustrative tool and with reference to the accompanying drawings thereof, in which:

FIG. 1 is an axial section of a fastener driving tool in its barrel breech closed and unlocked and uncocked condition;

FIG. 2 is a transverse section of the tool taken on line Il--II of FIG. 1 and showing a pawl engaged in a longitudinal slot of the barrel which is unlocked;

FIG. 3 is a section similar to that of FIG. 2 and showing disengagement of the pawl when the barrel is relatively turned to locked position;

FIG. 4 is a perspective detail of barrel and receiver interlock portions looking in the general direction of the arrows IV-IV in FIG. 1, and

FIG. 5 is a view in side elevation of the barrel and indicating angular relation of its guide slot and breech locking threads.

dinally slidable and rotatable in a tubular main housing or receiver 14. A handle housing 16 is secured externally to the breech end of the receiver. For driving a fastener (not shown) which may be mounted in the muzzle end of a tubular guide 20 coaxial with a resilient (desirably polyurethane) buffer 22 in an end of the barrel 12, a piston-type ram 24 is axially slidable from a first position shown in FIG. 1 to a final or fired, leftward position indicated by dash lines wherein a head portion 26 of the ram abuts the buffer 22. Preferably the ram is tapered as at 30 (FIG. 1) to radially expand the bore of the buffer 22 on overdrive. I

As shown in FIG. 1, a flange 28 of the guide 20 is threadedly retained against the muzzle end of the barrel and an inner end of the guide abuts the buffer 22. A safety barrel-turning collar 32 is mounted on the guide 20 by a pair of guide lock screws 34, 34 respectively slidable in longitudinal slots 36 of the collar and threaded into the barrel.

As clearly shown in FIG. 5 the barrel 12 has its breech end formed with sets of circumferentially interrupted locking threads 38. Also, for purposes hereinafter explained, the barrel is formed with a longitudinal slot 40 aligned with an interruption or non-threaded breech portion. An end portion 42 of the slot 40, as indicated in FIGS. 2, 3, and 5 is angularly offset for permitting pivotal movement therein of one arm of a twoarmed pawl 44 secured on a pin 46 mounted in bores in the receiver parallel to the barrel axis. The arrangement is such that when, as in FIG. 2, the sets of barrel threads 38 are not in locking engagement with corresponding sets of interrupted locking threads 48 formed in an action or breechblock 50 secured in the breech end of the receiver, an end of a coil spring 52 nested in the receiver urges a portion of the pawl 44 into the barrel slot 40. In such slot engaging position the pawl can engage the driven ram head 26, and accordingly subsequent relative forward, i.e., muzzleward, movement of the barrel l2 enables the pawl 44 to restore the ram 24 to its initial position therein indicated in FIG. 1.

The receiver 14 has an open-sided portion 54 (FIG. 1) providing access to a barrel breech bore 56, when the barrel is unlocked and retracted from the breechblock, for loading a cartridge or the like therein. When a charge is loaded, the barrel may be relatively rotated a fraction of a turn by means of the collar 32 to lock the barrel threads 38 with the breechblock locking threads 48 as shown in FIG. 3. This simultaneously effects disengagement of the pawl 44 from the barrel slot 40 against resistance of the spring 52. Now, with a stud or other fastener to be driven inserted in the guide 20, the latter may be brought to bear endwise on a structure to cook the tool in preparation for firing. Resulting relative displacement to the right (in FIG. 1) of the guide flange 28, and hence of the barrel 12, cocks a compression spring of firing mechanism which may,

- for instance be of conventional cartridge rim impacting right and thereby causes a firing pin 68 then engaging a shoulder 70 of the sear 64 to be moved to the right against resistance of a firing pin spring 72 nested in the housing. It will accordingly be understood that in its cocked condition an end of thesear 64 will be disposed for engagement by a projection 74 of a trigger 76 pivoted on a pin 78 in the receiver 14. The trigger is biased clockwiseas seen in FIG. 1 by a spring 80. Upon actuation of the trigger counterclockwise to displace the sear shoulder 70 against resistance of the spring 66, the firing pin is released to extend into striking engagement with the firing rim of the cartridge in the chamber 56. The consequently generated gases of combustion expand to cause the ram 24 to drive the fastener from the guide and into the structure.

After firing the barrel is reversely rotated by means of the collar 32 relative to the receiver 14 to disengage the threads 38,48 whereupon relative movement to the left of the barrel in the receiver, as now permitted by the pawl 44 riding longitudinally in the slot 40, restores the ram piston head 26 to its initial position-and readies the tool for reloading. A spring 82 provided in a groove on the ram head yieldingly retains it in restored position. With the, tool reloaded the barrel breech is closed and the relative rotation of the locking threads 38,48 not only seals the firing chamber but disengages the safety pawl 44 from the slots 40,42 as shown in FIG. 3. The positively pivoted pawl 44 being out of the way, if overdrive occurs the ram portion 30 will expand the buffer bore radially, and great amounts of energy may thusbe repeatedly absorbed without permanent distortion of the buffer.

The barrel 12 is preferably also formed with stop means for preventing unlocking of the barrel breech when the tool is armed, i.e., loaded and locked. To this end the barrel, as shown in FIGS. 4 and 5, has adjacent its end and circumferentially spaced pads, three of which are designated 84 and a fourth pad having reduced interlock projection 86. The latter is shown in different positions in FIG. 4 and arranged to circumferentially abut with a complemental land 88 internally formed on the receiver 14 when the barrel breech has been closed and locked, insuring that the barrel 12 is always locked into the housing 16 in the same orientation. Thus the projection 86 may further serve to prevent the barrel breech from being excessively rotated on being shifted to open position. Moreover, if the pawl 44 should be broken, the pad arrangement 84 prevents arming the tool with its breech unlocked.

Reviewing operation of the tool briefly, it is shown in an unlocked and uncocked condition in FIG. 1 but carries a charge in the chamber 56. The pawl 44 now extends into the slot 40 so that the barrel 12 cannot be relatively movedrearwardly to cock the firing mechanism because the end portion 42 of the slot 40 will engage the pawl. An operator locks the tool by rotating the barrel, turning the collar 32 one-eighth of a revolution clockwise as viewed in FIG. 2. This rocks the pawl- 44 to an inoperative position out of the slot 40 as shown in FIG. 3 and also causes the sets of threads 38,48 to interengage for locking the barrel 12 into the housing 16. Also, this rotation aligns the barrel pads 84 with their complementary housing recesses allowing rearward movement of the barrel 12 to take place. The tool being uncooked and locked, but with the ram head 26 in firing position, the fastener to be driven is placed into the detachable guide 20. Next the tool is cocked by bringing the muzzle end of the guide 20 to contact the structure which is to receive the fastener and bearing on the housing 16 to urge it forwardly relative to the barrel 12. The tool is now cocked and locked, but if the operator tries to cock the tool while it is unlocked, the barrel engages the pawl 44, and the pads 84 abut the receiver 14 to prevent him. In attempting to lock the barrel, the operator cannot rotate it excessively although the pawl 44 is out of the slot 40 because the projection of the pad 86 will engage either an edge of the receiver recess or the receiver land 88. On triggering the tool to cause the ram 24 to explosively drive the fastener, should the structure insufficiently resist fastener entry the buffer 22 will stop the ram. Upon removal of the tool from the work, the operator turns the barrel one-eighth revolution counterclockwise (as viewed in FIGS. 2, 3) to disengage threads 38,48 thus allowing the pawl 44 to return into the slot 40. By axially pulling the collar 32 away from the housing 14, the ram 24 travels forwardly with the barrel 12 (due to their frictional engagement at the spring 82), and the head 26 of the ram engagesthe pawl 44 so that the ram is stopped and returned to its firing position in the barrel. Lastly the operator places a new charge in the bore 56 through the opening 54 and slides the barrel rearwardly to its condition shown in FIG. 1.

Summing up, the several safety features are:

l. pawl 44 prevents tool cocking when the barrel 12 is not locked to the housing 16 so that the tool cannot be fired when unlocked and rapid separation of the barrel is avoided.

2. pads 84 also insure the tool is not cocked in unlocked condition.

3. pads 84 prevent unlocking the barrel from the housing while the firing mechanism is cocked.

4. pad 86 prevents excessive rotation of the barrel, which would eliminate the safety afforded by the pawl 44.

5. possibility of air-firing," i.e., without being pressed against a structure, is eliminated, since the collar 32 cannot be pulled to cock the tool as it engages the housing 16 before cocking occurs.

Of these features, the last three may be deemed optional.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In an explosively actuated fastener driving tool, a receiver, a barrel axially slidable and rotatable in the receiver, a ram slidable in the barrel between an initial firing position and a second fired position, the barrel having its breech end formed with circumferentially interrupted sets of threads for locking the barrel in the receiver in breech-closed relation and having a longitudinal slot extending in alignment with the thread set interruption, and a pawl movably carried by the receiver and adapted, when the barrel breech is unlocked, to be engaged in the barrel slot.

2. A tool as in claim 1 wherein the barrel slot has a circumferentially offset portion at its muzzle end, the pawl is pivotally mounted in said receiver, and spring means biases a portion of the pawl into the longitudinal portion of the slot for engagement with a portion of the ram in its second position.

3. A tool as in claim 2 wherein the pawl is two-armed and mounted on a pivot pin parallel with the axis of the barrel, and a coil spring bearing on the receiver and on one arm of the pawl urges the other arm of the pawl into the longitudinal portion of the barrel slot.

4. In an explosively actuated fastener driving tool having a receiver for housing the breechblock and firing mechanism, a barrel axially slidable and rotatable in the receiver and having a muzzle portion extending beyond the receiver, the breech end of the barrel and the breechblock being formed with circumferentially interrupted threads engageable to lock said breech end in operative relation to the firing mechanism, the firing mechanism being energizable by relative longitudinal movement of the barrel and receiver, and an interlock means formed on said muzzle portion of the barrel for cooperation with the receiver whereby .the barrel breech is prevented from being unlocked when the tool is armed.

5. A tool as set forth in claim 4 wherein the interlock means comprises a circumferential series of pads on the barrel, each of said pads being receivable in a complemental mating recess in an end of the receiver, and one of said barrel pads having a reduced, projection engageable with a complemental land of the receiver.

6. An explosive fastener driving tool comprising a housing, a barrel axially movable and rotatable therein between a breech open and breech closed position, a spring-pressed firing mechanism including a breechblock in the breech end of the housing and cocked by relative movement of the barrel and the housing when the latter is urged toward a structure into which the fastener is to be driven, and means at the muzzle end of the barrel for rotating it into breech closed and locked relation to the breechblock, said means being longitudinally movable on the barrel and having a formation for interlocking with the housing in one rotational position to prevent unlocking of the barrel breech when the tool is cocked.

7. A tool as set forth in claim 6 wherein the breechblock and the breech end of the barrel are respectively formed with circumferentially interrupted sets of locking threads, the barrel is adapted slidably to guide a fastener driving ram, the barrel being formed with a longitudinal slot having an offset portion remote from the breech end, and a pawl movably mounted in the offset portion of the barrel slot is engageable with a portion of the ram when the barrel breech is axially moved from locking relation with the breechblock.

8. A tool as set forth in claim 7 wherein the pawl is pivotally supported by the housing, a resilient buffer is disposed in the muzzle of the barrel and formed with a bore wall coaxial with the ram and adapted to be radially enlarged upon engagement therewith of a trailing portion of the ram, such engagement being potentially permitted by breech locking movement of the barrel to clear the pawl from the barrel slot.

9. An explosive fastener driving tool comprising a housing, a barrel axially movable and rotatable therein between a breech open and a breech closed position, a breechblock in the housing having a threaded formation for locking the barrel in breech closed relation, 2 ram axially slidable in the barrel and having an axially tapering portion, a pawl pivotal in the housing and having a portion extending radially through a longitudinal slot in the barrel and partly into the path of the ram, said pawl being cammed out of said path by rotation of the barrel into locking relation with the breechblock, and a resilient, tubular buffer on the other side of the pawl from the breech end of the tool, the bore of the buffer being adapted to be radially expandable upon engagement by said ram tapering portion for absorbing ram energy in the event of overdrive.

10. An explosively actuated fastener driving tool comprising a housing, a barrel axially and rotatably slidable in the housing, a firing mechanism in the housing and arranged to be cocked by relative rearward movement of the barrel and thereafter to be actuated to cause ignition of an explosive charge in the barrel, interlocking means for locking the barrel into the housing and adapted to release the barrel for forward sliding movement upon relative rotation of the barrel and the housing, a fastener driving ram movable in the barrel between a firing position and a driven position, a ram return member mounted on the housing and movable between an inoperative position and an operative position in which it extends through a longitudinal slot in the barrel for engaging and holding the ram stationary relative to the housing so that forward sliding movement of the barrel returns the ram to its firing position, and stop means for preventing rearward movement of the barrel to cock the firing mechanism unless the barrel is locked to the housing by said interlocking means. =l= 

1. In an explosively actuated fastener driving tool, a receiver, a barrel axially slidable and rotatable in the receiver, a ram slidable in the barrel between an initial firing position and a second fired position, the barrel having its breech end formed with circumferentially interrupted sets of threads for locking the barrel in the receiver in breech-closed relation and having a longitudinal slot extending in alignment with the thread set interruption, and a pawl movably carried by the receiver and adapted, when the barrel breech is unlocked, to be engaged in the barrel slot.
 2. A tool as in claim 1 wherein the barrel slot has a circumferentially offset portion at its muzzle end, the pawl is pivotally mounted in said receiver, and spring means biases a portion of the pawl into the longitudinal portion of the slot for engagement with a portion of the ram in its second position.
 3. A tool as in claim 2 wherein the pawl is two-armed and mounted on a pivot pin parallel with the axis of the barrel, and a coil spring bearing on the receiver and on one arm of the pawl urges the other arm of the pawl into the longitudinal portion of the barrel slot.
 4. In an explosively actuated fastener driving tool having a receiver for housing the breechblock and firing mechanism, a barrel axially slidable and rotatable in the receiver and having a muzzle portion extending beyond the receiver, the breech end of the barrel and the breechblock being formed with circumferentially interrupted threads engageable to lock said breech end in operative relation to the firing mechanism, the firing mechanism being energizable by relative longitudinal movement of the barrel and receiver, and an interlock means formed on said muzzle portion of the barrel for cooperation with the receiver whereby the barrel breech is prevented from being unlocked when the tool is armed.
 5. A tool as set forth in claim 4 wherein the interlock means comprises a circumferential series of pads on the barrel, each of said pads being receivable in a complemental mating recess in an end of the receiver, and one of said barrel pads having a reduced, projection engageable with a complemental land of the receiver.
 6. An explosive fastener driving tool comprising a housing, a barrel axially movable and rotatable therein between a breech open and breech closed position, a spring-pressed firing mechanism including a breechblock in the breech end of thE housing and cocked by relative movement of the barrel and the housing when the latter is urged toward a structure into which the fastener is to be driven, and means at the muzzle end of the barrel for rotating it into breech closed and locked relation to the breechblock, said means being longitudinally movable on the barrel and having a formation for interlocking with the housing in one rotational position to prevent unlocking of the barrel breech when the tool is cocked.
 7. A tool as set forth in claim 6 wherein the breechblock and the breech end of the barrel are respectively formed with circumferentially interrupted sets of locking threads, the barrel is adapted slidably to guide a fastener driving ram, the barrel being formed with a longitudinal slot having an offset portion remote from the breech end, and a pawl movably mounted in the offset portion of the barrel slot is engageable with a portion of the ram when the barrel breech is axially moved from locking relation with the breechblock.
 8. A tool as set forth in claim 7 wherein the pawl is pivotally supported by the housing, a resilient buffer is disposed in the muzzle of the barrel and formed with a bore wall coaxial with the ram and adapted to be radially enlarged upon engagement therewith of a trailing portion of the ram, such engagement being potentially permitted by breech locking movement of the barrel to clear the pawl from the barrel slot.
 9. An explosive fastener driving tool comprising a housing, a barrel axially movable and rotatable therein between a breech open and a breech closed position, a breechblock in the housing having a threaded formation for locking the barrel in breech closed relation, a ram axially slidable in the barrel and having an axially tapering portion, a pawl pivotal in the housing and having a portion extending radially through a longitudinal slot in the barrel and partly into the path of the ram, said pawl being cammed out of said path by rotation of the barrel into locking relation with the breechblock, and a resilient, tubular buffer on the other side of the pawl from the breech end of the tool, the bore of the buffer being adapted to be radially expandable upon engagement by said ram tapering portion for absorbing ram energy in the event of overdrive.
 10. An explosively actuated fastener driving tool comprising a housing, a barrel axially and rotatably slidable in the housing, a firing mechanism in the housing and arranged to be cocked by relative rearward movement of the barrel and thereafter to be actuated to cause ignition of an explosive charge in the barrel, interlocking means for locking the barrel into the housing and adapted to release the barrel for forward sliding movement upon relative rotation of the barrel and the housing, a fastener driving ram movable in the barrel between a firing position and a driven position, a ram return member mounted on the housing and movable between an inoperative position and an operative position in which it extends through a longitudinal slot in the barrel for engaging and holding the ram stationary relative to the housing so that forward sliding movement of the barrel returns the ram to its firing position, and stop means for preventing rearward movement of the barrel to cock the firing mechanism unless the barrel is locked to the housing by said interlocking means. 